This patent relates to the field of swimmer training devices, for permitting exercise in restricted spaces in swimming pools.
Such devices in the prior art include:
A number of devices consist of cables attached at one end to the waist of the swimmer and at the other end to the wall of a pool, or to a device fixed to the side of the pool.
Soviet Patent 636001, with an English abstract, discloses a swimming device in which the feet are suspended on fixed rods angled at each other. The rods apparently contain instrumentation to determine the power with which the swimmer swims. The feet are engaged by the apparatus and are not free to move.
U.S. Pat. No. 4,551,108 discloses a device attached at two points to a flotation vest and attached at opposite ends of the pool to prevent motion in any direction (FIG. 4). This is an exercise device for weight reduced running; it does not promote swimming.
German Patent 1,190,849 shows a swim training device attached to a belt around the waist. There appears to be no flotation. The swimmer is attached to a belt which passes over a pulley then back to a weight so that the force of the swimmer apparently pulls against the weight to provide resistance. There appear to be two stabilizing lines attached to two points on the wall of the pool.
An extract from a Sports Illustrated article of Sep. 17, 1984 apparently describes a tether attached to a swimmer which appears to rise vertically from the pool, where it is attached to an overhead pole in order to be free of the swimmer's legs.
U.S. Pat. No. 4,948,117 discloses a form of tether which attaches to the ankles of the swimmer. Two such tethers are required but they are apparently moored to a single point.
German Patent 197806 discloses an apparatus for measuring the tractive effort of a swimmer in which a single tether to a swimmer runs over a pulley to a spring scale. The device also has a timer so as to measure the force exerted during a period of time.
German Patent 2821-029 discloses another form of such device in which a single tether passes through a pulley against a spring to vary the resistive force against which the swimmer must exercise.
U.S. Patent 4,247,096 discloses a portable swim trainer device which has a frame fixedly attached to the side wall of a pool, extending to a point above the level of the water. The swimmer is suspended by a spring or bungee cord, a single cable running from the frame to a waist belt worn by the swimmer.